1. Field of the Invention
This invention relates to the construction of storage tanks.
2. Description of the Prior Art
Fiber glass reinforced plastic storage tanks offer many advantages over tanks made of other materials which has resulted in an increasing and widespread use of these tanks. With proper selection of material, they are inert chemically so that they can be used for storing chemicals and with any liquid the problem of corrosion is lessened. Furthermore, they are durable and strong. They can be made at relatively low cost, under factory-controlled conditions.
However, such reinforced plastic storage tanks have been limited almost exclusively to tanks of relatively small size. This is because tanks of larger diameters cannot be transported either by truck or rail due to the dimensional limits for loads in such transportation. Larger tanks exceed permissible load widths. Hence, factory production has not been possible. Some larger tanks have been constructed by fabricating the tank on the site of its use so that no transportation is required. There are several drawbacks to such a procedure, principally involving the increased time required for production. A controlled environment is needed for constructing such tanks which cannot be realized even with the use of a temporary air supported structure. Temperatures may fluctuate reducing or extending the cure time of the resin used for the tank as well as making working conditions somewhat unpleasant. Also, a project of this type requires transportation of equipment to the site where the tank is to be produced, which is a relatively expensive operation. Skilled personnel normally must be sent to the place of the tank project to further add to the cost. Inherently it is more difficult to control the manufacturing operation in the field so that on-site tank fabrication requires considerable effort to obtain quality approaching that of factory production. Thus, large tank construction at the site of use of the tank is costly as well as being relatively slow and cumbersome.